1. Field of Application
The present invention relates to a pressure sensor for measuring the pressure within a combustion chamber of an internal combustion engine.
2. Description of Related Art
By measuring the pressure within a combustion chamber of an internal combustion engine, it becomes for example possible to detect occurrence of engine knock, thereby enabling the engine operation to be more closely controlled. A combustion chamber pressure sensor which is utilized for such a pressure measurement function may be an independent device, or may be integrated with another device that is installed in a combustion chamber. A combustion chamber pressure sensor may for example be integrally combined with an engine spark plug, or with a combined ignition coil and spark plug. This is described for example in Japanese patent publication No. 2000-277232. However a basic problem exists with prior art subjected to the pressure of the combustion chamber and generates a pressure measurement signal accordingly. In the prior art, a substantial level of engine vibration is transmitted through the engine block and reaches the pressure sensing element, and results in occurrence of noise in the pressure measurement signal. This noise results in lowering of the pressure measurement accuracy. In particular, the existence of such noise renders it difficult to accurately detect the occurrence of engine knock, by monitoring pulsations in the pressure measurement signal.